fix org reference for central node

[aboydnw]

Root cause

config.toml had central_repository = "DevSeed Team" (no org prefix), but the CSV data on disk has developmentseed/DevSeed Team (with org prefix). When the Jinja template passed "DevSeed Team" as REPO_CENTRAL to the visualization, prepareData created nodes from the CSV with id: "developmentseed/DevSeed Team", so the lookup d.id === "DevSeed Team" failed.

This likely happened during the refactoring, probably because I removed the center node visualization. I made a followup ticket to fully remove #40
The config value was shortened to just the display name, but the CSV (which was generated earlier with the full owner/repo format) wasn't regenerated.

Two changes made:

1. config.toml — restored the full owner/repo format: central_repository = "developmentseed/DevSeed Team". This matches the CSV data and the convention used by every other repository in the config.
2. python/templates/index.html.jinja line 54 — changed the title display from {{ central_repository }} to {{ central_repository.split('/')[-1] }} so the heading still renders as "DevSeed Team" rather than the full path.